Question

Glycolysis activity 1: Metabolic pathway puzzle Try to complete the activity without using the textbook. 1. Slides 4 and 5 show the 10 reactions for glycolysis, but some of the molecules are missing. Draw the missing molecules in the proper place (on the handout). The missing molecules are shown on the next slide, you have to use the clues on the handout and your organic chemistry knowledge to figure out where each molecule belongs. 3. In the red dotted boxes add one of the following as needed: ATP/ADP/AMP/NAD+/NADH+H+/H2O

Answer 1

Glycolysis is the chief pathway involved in the metabolism of glucose. It converts six-carbon compound glucose into three-carbon compound pyruvate. In the overall glycolytic process, one molecule of glucose is converted to two molecules of pyruvate and 2 molecules of ADP get phosphorylated into 2 molecules of ATP.

Reaction 1. Glucose to Glucose-6-phosphate. In this reaction, the C6 of the glucose gets phosphorylated by the hexokinase. ATP act as a phosphoryl group donor.

Reaction 2. Glucose 6-phosphate to Fructose-6-phosphate. It involves an aldose-ketose isomerization by phosphohexoseisomerase.

Reaction 3. Fructose 6-phosphate to Fructose-1,6-Bisphosphate. In this, Fructose 6-phosphate gets phosphorylated at C1 position by the enzyme phosphofructokinase-1 (PFK-1). ATP act as a phosphoryl group donor. It is a major regulatory step of glycolysis.

Reaction 4. Fructose 1,6-Bisphosphate to glyceraldehyde 3-phosphate and dihydroxyacetone phosphate. In this, Aldolase enzyme catalyzes the cleavage of Fructose 1,6-Bisphosphate (a 6-carbon compound) into two triose Phosphates glyceraldehyde 3-phosphate and dihydroxyacetone phosphate ( 3-carbon compounds).

Reaction 5. Dihydroxyacetone phosphate to Glyceraldehyde 3-phosphate. Glyceraldehyde 3-phosphate and dihydroxyacetone phosphate can be interconverted by the enzyme phosphotriose isomerase.

Reaction 6. Glyceraldehyde 3-Phosphate to 1,3-Bisphosphoglycerate. In this, glyceraldehyde 3-phosphate gets oxidized to 1,3-bisphosphoglycerate, catalyzed by glyceraldehyde-3-phosphate dehydrogenase. It is an NAD+ dependent reaction that removes the H ion and replace it with the phosphoryl group donated by the inorganic phosphate.

Reaction 7. 1,3-Bisphosphoglycerate to 3-phosphoglycerate. The reaction catalyzed by phosphoglycerate kinase, which removes the phosphoryl group from 1,3-Bisphosphoglycerate and transfers it to ADP molecule generating ATP. This is the first of the two energy-conserving reactions of glycolysis that ultimarely lead to the formation of ATP.

Reaction 8. 3-Phosphoglycerate to 2-Phosphoglycerate. This reaction involves an irreversible shift of the phosphoryl group between C-2 and C-3 of glycerate catalyzed by the phosphoglycerate mutase.

Reaction 9. 2-Phosphoglycerate to Phosphoenolpyruvate. It is a dehydration reaction catalyzed by Enolase.

Reaction 10. Phosphoenolpyruvate to Pyruvate. Therein, the phosphoryl group from phosphoenolpyruvate is transferred to ADP, catalyzed by pyruvate kinase. this is the second energy-conserving reaction generating second ATP molecule.

The pictures depict only the missing molecules in the reactions.

HO-CH2 TREACTION 1 ATP ADP [Herokinase) HONOM /OH (Guicose OH no ou for OH Glucose -6- Phosphate) REACTION-3 -O-CH₂O CH-04 ATP ADDO-P-O-CH₂ CH₂-O-P-o- I HO OH (phosphofructo OM Kinase [Fructose-6-p fructose-6-P freuectose-1,6-bisphosphate REACTION 4 6-H fructose-1,6-BP CH₂-O-P-01 НЕС - ОН Taldolase e=0 H-E-H hora 1 - CH, OH toihydroxyacetone phosphate + +

REACTIONG Pop Cotyceratelydenis H-&-OH NAD NADHI H-6-H etc. V 13 3- Bisphospho glycerate. -o-P=0 Tinorganic dehydrogenase] o Phosphate) LGlyceraldehyde -3.p] REACTION-7 ADP LATP 1,3-Bisphosphor glyceoate phospho geyertale c=0 | HC=OH | M-e-H kinase -o-P=0 (3-phosphogy cerate)

REACTIONG H- C-0 th H-C-H H-c-o-P=0 H2O H-C-H HO OH (Enolase 12- phospho gucerate) (phosphoenol Pyruvate]